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Cell size, photosynthesis and the package effect: an artificial selection approach
Author(s) -
Malerba Martino E.,
Palacios Maria M.,
Palacios Delgado Yussi M.,
Beardall John,
Marshall Dustin J.
Publication year - 2018
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.15163
Subject(s) - photosynthesis , oxygen evolution , chlorophyta , chlorophyll a , biology , cell size , chlorophyll , algae , oxygen , botany , phytoplankton , photosynthetic pigment , interspecific competition , biological system , biophysics , ecology , chemistry , microbiology and biotechnology , organic chemistry , electrode , nutrient , electrochemistry
Summary Cell size correlates with most traits among phytoplankton species. Theory predicts that larger cells should show poorer photosynthetic performance, perhaps due to reduced intracellular self‐shading (i.e. package effect). Yet current theory relies heavily on interspecific correlational approaches and causal relationships between size and photosynthetic machinery have remained untested. As a more direct test, we applied 250 generations of artificial selection ( c . 20 months) to evolve the green microalga Dunaliella teriolecta (Chlorophyta) toward different mean cell sizes, while monitoring all major photosynthetic parameters. Evolving larger sizes (> 1500% difference in volume) resulted in reduced oxygen production per chlorophyll molecule – as predicted by the package effect. However, large‐evolved cells showed substantially higher rates of oxygen production – a finding unanticipated by current theory. In addition, volume‐specific photosynthetic pigments increased with size (Chl a + b ), while photo‐protectant pigments decreased (β‐carotene). Finally, larger cells displayed higher growth performances and F v / F m , steeper slopes of rapid light curves (α) and smaller light‐harvesting antennae (σ PSII ) with higher connectivity (ρ). Overall, evolving a common ancestor into different sizes showed that the photosynthetic characteristics of a species coevolves with cell volume. Moreover, our experiment revealed a trade‐off between chlorophyll‐specific (decreasing with size) and volume‐specific (increasing with size) oxygen production in a cell.